Embolectomy catheter



April 1969 T. J. FOGARTY 3,435,826

EMBOLECTOMY CATHETER Filed May 27, 1964 INVENTOR. THOMAS J. FOGARTYUnited States Patent 3,435,826 EMBOLECTOMY CATHETER Thomas J. Fogarty,Portland, Oreg., assiguor to Edwards Laboratories, Inc., Santa Ana,Calif., a corporation of California Continuation-impart of applicationSer. No. 208,967, July 10, 1962. This application May 27, 1964, Ser. No.370,430

Int. Cl. A61m 25/00, 29/02; A61'b 17/24 U.S. Cl. 128-348 18 ClaimsABSTRACT OF THE DISCLOSURE A balloon catheter in which the balloonmaterial is longitudinally stretched when deflated causing the balloonto contract circumferentially and smoothly hug the catheter body. Avenous thrombectomy catheter having a soft and highly flexible tipportion capable of doubling back against the catheter body for upstreampassage through the valve leaflets in a vein.

This invention relates to improvements in a balloon catheter forembolectomy purposes.

This application is a continuation-in-part of my copending applicationtitled, Method of Vascular Surgery or the Like and Instrument Therefor,Ser. No. 208,967 filed July 10, 1962, now abandoned.

In the use of a balloon catheter to remove a blood clot, the location ofthe clot is first determined and then an incision is made in the vesselcontaining the clot or in some branch of the vessel which communicatestherewith. The nearest point of access where such incision may be mademay in some cases be at a considerable distance from the clot, dependingupon the part of the body where the clot is located. The catheter isinserted through the incision and threaded through the vessel or branchleading to the clot. With the balloon deflated, the tip of the catheteris pierced through the clot and the threading movement continued untilthe balloon portion of the catheter has passed entirely through theclot. Then the balloon is inflated on the remote side of the clot. Thecatheter may then be withdrawn, the balloon behind the clot acting as adrag to push the clot ahead of it until the clot reaches the region ofthe incision where it can be readily withdrawn.

Emboli can occur to many vessels of the body. These vessels may bereltaively normal or diseased. Atherosclerosis is by far the most commondisease affecting these vessels. When affected by this process, vesselsbecome quite tortuous and have regions of marked angulation andnarrowing. Under such conditions clots occurring in the vessels resistthe passage of conventional relatively straight and stiff catheters. Ifundue force is exerted, the cather may pass through the vessel wall orcause disruption of atherosclerotic material.

Many difliculties attend the removal of clots with balloon catheters.After the catheter has pierced through the clot, the balloon is inflatedand the clot removed along with the catheter. During the dragging of aclot along the vessel, there is a tendency for the resistance to removalto cause the balloon portion of the catheter to slide over the tip ofthe catheter. Sometimes it is necessary to reduce the inflation of theballoon during removal and during such deflation this distal end portionof the balloon may become caught on the catheter tip causing the tip toangulate acutely, inflating fluid being trapped in the distal endportion of the balloon so that it does not deflate as desired.

Other problems also exist. Arteries and veins because of their specificindividual functions possess certain ana- 3,435,826 Patented Apr. 1,1969 tomical differences. Arteries, performing an efferent circulatoryfunction, are relatively thick walled vessels without valves. Veins,having as their main function the return of blood to the heart, incontrast, are thin walled vessels containing numerous valves.Consequently, the type of clot forming in these two structures issignificantly different. An arterial embolus is firmer and of greaterdensity than the clots occurring in the veins.

Because of these differences and, also, for the sake of efliciency, thestructure and design of catheters for the extraction of clots from suchtype of vessel must also differ. The catheters designed for theextraction of venous thrombi must be of a more pliable nature in orderto avoid perforation of the venous wall. In addition, some mechanismmust be available to enable a catheter to pass through the venous valveswhich offer obstruction to catheters not specifically designed for thispurpose. Particularly, for the extraction of venous clots fromperipheral portions of the body, the catheter must be designed so thatthe instrument can be atraumatically conducted past the valves.

The general object of the present invention is, therefore, to provideimproved balloon catheters for embolectomy purposes which will overcomethese problems and which will overcome the deficiencies and.shortcomings of conventional catheters. Other objects are to provideimproved forms of balloon structure which will not stretch beyond thetip of the catheter, which will not trap air in the distal portion ofthe balloon when it is desired to deflate the balloon and to providediiferent forms of constructions for catheters to be used in arteriesand veins in order to meet the particular problems encountered in eachcase.

In the present catheters, the danger of passing the catheter through thewall of the vessel or causing disruption of atherosclerotic material isavoided by covering the distal extremity with soft plaible material.

In the case of the catheter for venous thrombectomy, a very pliable tipis provided extending forward from the distal end of the balloon. Thepliability of the tip is of such degree that the obstruction offered bythe valvular face causes acute angular deformity of the tip. The forcenecessary to cause this acute angulation is far below the force requiredto cause valvular or wall damage to the venous system. As the tipyields, it doubles back to such a position that it falls through thevalvular orifice. The catheter may then be continued on until anothervalve is met and the procedure repeated.

The invention also includes improvements in the manner of attaching theballoon to the catheter body and the arrangement of fluid passagesthrough the catheter body for inflating and deflating the balloon sothat all parts of the balloon are insured of deflating when desired.

Still other objects and advantages will become :apparent and theinvention will be better understood with reference to the followingdescription of two preferred embodiments of the catheter illustrated onthe accompanying drawing. Various changes may be made, however, in thedetails of construction and arrangement of parts and all suchmodifications within the scope of the appended claims are included inthe invention.

In the drawing:

FIGURE 1 is a general view of a catheter embodying the features of theinvention for arterial thrombectomy with certain parts shown in section;

FIGURE 2 is a view of the distal end of the catheter of FIGURE 1 withthe balloon inflated and shown in section;

FIGURE 3 is a sectional view of the balloon of FIG- URES l and 2 inrelaxed condition before installation;

FIGURE 4 is a longitudinal sectional view of the distal 3 end portion ofa catheter for venous thrombectomy; and

FIGURE 5 is a longitudinal sectional view through a vein showingmanipulation of the catheter of FIGURE 4 to pass it through a valvularopening.

The arterial catheter tube in FIGURE 1 is composed of flexible plasticmaterial and contains a lumen or bore 11 to convey fluid for inflatingand deflating the balloon. The proximal end of the tube is connected toone side of the valve 12 and the other side of the valve is connected toa syringe 13.

At its distal end the tube 10 has a reduced portion 15 provided withradial openings 16 staggered around the tube and a still further reducedextremity 17 beyond the end of bore 11. The surface of the tube isprovided with minute projections at 18 and 19 for securing end portionsof the balloon 20. The openings 16 extend along substantially the entirelength of the balloon to a point close to the solid extremity 17.

As shown in FIGURE 3, the ballon 20 is manufactured as a closed endrubber tube having a thickened end portion 21 which is soft and pliable.In assembly, the balloon is drawn over the end of the catheter tip bygripping the skirt 20a of the balloon and pulling tightly, forcing thecatheter end portion 17 into the balloon and imparting considerablelongitudinal stretch to the material of the balloon. With the balloonheld in this position, a layer of thread 22 is wound around the endportion 17, squeezing the rubber of the balloon tightly against andbetween the projections 18, causing these projections firmly to grip thematerial of the balloon. The stretch of the balloon and tension of thethread in winding beginning at the distal end of the winding area forcesthe rubber to compress to a smaller diameter. As the winding progressesin a proximal direction, the tension of the thread forces additionalstretch to occur under the winding with the result that the outsidediameter of the Wound thread is slightly smaller than the final deflateddiameter of the balloon and the main body of the catheter tube 10.

With the balloon still held in longitudinally stretched condition asdescribed, a proximal binding 23 is applied in a similar manner over theprojections 19. Just prior to termination of the binding 23 in proximaldirection, excess balloon materal including the skirt 20a is cut off sothat the last few turns of the thread cover up any ragged edges of theballoon material. A suitable air drying cement or the like is thensoaked into both of the bindings 22 and 23 for sealing and locking thebindings in place and providing a smooth surface thereon, Thus, theballoon in FIGURE 1 is not in a relaxed condition while deflated but isstretched in a longitudinal direction, causing it to shrink in diameterand hug closely and smoothly the smooth surface of the reduced cathetertube portion 15. The binding 23 compresses the balloon material so thatthe outside diameter of the binding is no larger in diameter than themain portion of the tube 10 and the outside diameter of thelongitudinally stretched and deflated balloon between the bindings 22and 23 is the same.

The taper and the softness of tip 21 prevents damage to the wall of theartery as the catheter is threaded therein. Thus, the distal end of thecatheter may be pierced through a clot and the balloon inflated on theremote side of the clot, preferably by means of a liquid expressed fromsyringe 13. When inflated, the balloon assumes a sausage shape as shownin FIGURE 2. Then, by closing valve 12 and withdrawing the catheter Withthe balloon inflated, the clot may be moved along the artery ahead ofthe balloon and pulled out of the incision where the catheter wasinserted.

In case there are constrictions in the artery, the balloon undergoes aprogressive contraction in passing through each constriction. Theopenings 16 are distributed in different radial directions along theentire length of tube portion 15 which is within the balloon to permitfree interflow of the inflating fluid from one end of the balloon to theother. Thus, even though the balloon may be constricted for a shortinterval tightly against the tube portion 15, a pocket of inflatingfluid cannot be trapped in the distal end of the balloon to stop thewithdrawal movement of the balloon. Inflating fluid from the extremedistal end of the balloon can pass through the most distal opening 16 toa more proximal portion of the balloon which has already passed throughthe constriction. The inflating fluid has free interfiow betweenopposite ends of the balloon through openings 16 under all conditions.

In this way the balloon readily adjusts itself to cross sectionalvariations in the lumen of the artery so as to pass relatively freelythrough constricted sections and maintain contact with the wall of thelumen to keep the clot moving ahead of the balloon. This insures againstthe balloon moving past the clot and leaving the clot in the artery whena severe constriction is encountered. In a similar way the balloonprogressively conforms to changing cross sectional shape of the lumen inthe artery to maintain full circumferential contact with the wall of thelumen at all times during withdrawal of the balloon and clot.

FIGURE 4 illustrates a modification for venous therombectomy. In thiscase the balloon 30 is provided with an elongated soft and floppy end 31extending beyond the tip 17 of catheter tube 10. In order to make theend 31 even more yieldable to bending, it is provided with a reducedneck at 32 adjacent the end of tip 17. Preferably, the end of tip 17 isslightly enlarged to a bulbous shape as indicated at 33. Balloon 31 issecured in a stretched condition the same as balloon 20 in FIGURE 1. Itis sausage shaped when inflated and performs in the same manner asballoon 20.

The mode of operation of end extension 31 is shown in FIGURE 5. Here theproblem is to thread the catheter through valve leaflets 40 in a vein Vin opposition to the direction of the flow of blood through the vein asindicated by the arrow 41. These valve leaflets are inclined in adownstream direction and present no obstruction to a catheter which isbeing threaded in a downstream direction. However, when the catheter isbeing threaded in an upstream direction, as shown in FIGURE 4, the valveleaflets 40 present an obstruction which deflects the tip of thecatheter away from the valve orifice and towards the Wall of the vein.

When this happens with the present catheter, the end 31 merely angulatesand shifts the neck portion 32 into a more centralized position in thevein in line with the valve orifice. Then, as the catheter is pushedforward, end portion 31 doubles back and neck 32 leads the catheterthrough the orifice in looped configuration. When end 31 is clear of thevalve, it straightens out in a forward direction and assumes itsoriginal shape until the next is encountered and then the describedoperation is repeated. In order to function in this manner the endportion 31 forward from neck 32 should not be longer than approximatelyhalf the inside diameter of the vein at the valve or valves which willbe encountered.

Notwithstanding the soft and floppy texture of end 31, it is stillcapable of piercing a clot in the vein. If it does not proceed straightforward through the clot, it is free to double back and pass through theclot in such configuration just as it passes through a valve obstructionin FIGURE 4.

The catheter in FIGURE 4 gives the surgeon the option of approaching theclot from either direction whereas heretofore it was only possible toapproach in a downstream direction in the case of a venous clot. When itis impossible to approach in a downstream direction, the presentcatheter gives the surgeon means for removing a clot which could notheretofore be removed. Also, by approaching the clot in an upstreamdirection, there is the advantage of withdrawing it in the downstreamdirection whereby it is much more easily moved through the valves atintervals along the vein.

Although the material of main body portions 10, 15 and 17 is describedas flexible, it is relatively stiff and hard in comparison with theparts 20, 21, 30, 31 and 32 made of the very soft balloon material. Themain body portions must be rigid enough to support the balloon and holdit in elongated sausage shape when inflated, to sustain the tension ofthe stretched balloon material when it is deflated and to push theforward portions of the catheter through all irregularities andangulations in the lumen of the vessel approaching the clot when theballoon is deflated.

The longitudinally stretched and tensioned condition of the balloonmaterial when deflated, whereby the balloon material smoothly andconstrictively hugs the supporting body portion 15, and the smoothtransitions from balloon 20 to binding 23 to tube in FIGURE 1, providesa uniform, smooth external surface capable of being inserted into arestricted incision in a vessel and through regions of angulation andconstriction of the lumen of the vessel without excessive friction andwithout frictionally deforming the balloon section. In passing throughrestrictions, the deflated balloon material does not tend to gather andbunch up at its trailing end so as to enlarge the diameter of thecatheter and impede its free sliding movement. This tendency has beenfound highly objectionable in conventional balloon catheters.

Having now described my invention and in what manner the same may beused, what I claim as new and desire to protect by Letters Patent is:

1. A catheter comprising a flexible tube, a balloon surrounding an endportion of said tube, openings in said tube distributed along the lengthof said balloon for the passage of fluid in inflating and deflating theballoon, and means securing opposite end portions of the balloon to saidtube with the balloon material stretched longitudinally between saidsecuring means and smoothly hugging said tube when the balloon isdeflated, said balloon having a closed end enclosing the end of saidtube for a short distance beyond said securing means at the distal endof the balloon, said closed end of the balloon having a thickenedportion relatively softer than said tube overlying and pro jectingbeyond the end of said tube and forming a soft tip on the catheter.

2. A catheter as defined in claim 1, said securing means comprising awinding such as thread.

3. A catheter as defined in claim 1, said tube having protuberancesunder said securing means to grip said end portions of the balloon.

4. A catheter as defined in claim 1, including a syringe and a valve onthe opposite end of said tube for inflating and deflating the balloon.

5. A catheter comprising a flexible tube, a balloon surrounding an endportion of said tube, openings in said tube distributed along the lengthof said balloon for the passage of fluid in inflating and deflating theballoon, and means securing opposite end portions of the balloon to saidtube with the balloon material stretched longitudinally between saidsecuring means and smoothly hugging said tube when the balloon isdeflated, said tube having a portion of reduced diameter Within saidballoon and said securing means so that the maximum diameter of saidsecuring means and deflated balloon does not exceed the diameter of themain portion of said tube, said reduced diameter portion of said tubebeing further reduced within said securing means at the distal end ofthe balloon.

6. A catheter as defined in claim 5, including a soft and floppy tip endportion on the catheter.

7. A catheter as defined in claim 6, said tip end portion projectingforward from a flexible reduced neck portion which permits said tip endportion to double back against the catheter in a return bend.

8. A catheter comprising a'flexible tube, a balloon surrounding an endportion of said tube, openings in said tube distributed along the lengthof said balloon for the passage of fluid in inflating and deflating theballoon, and means securing opposite end portions of the balloon to saidtube with the balloon material stretched longitudinally between saidsecuring means and smoothly hugging said tube when the balloon isdeflated, a soft and floppy tip end portion on the catheter, said tipend portion comprising a part of the balloon.

9. A catheter comprising a flexible tube having an end portion ofreduced diameter, a balloon surrounding said portion of reduceddiameter, said balloon having a closed end covering the end of said tubeand forming a tip on the catheter, openings in said tube distributedalong the length of the balloon for inflating and deflating the balloon,means securing end portions of the balloon to said tube, and projectionson the surface of said tube under said securing means for gripping theballoon material, said balloon material being stretched longitudinallybetween said securing means and smoothly hugging the surface of saidtube when the balloon is deflated.

10. A catheter comprising an elongated hollow main body made of flexibleplastic material which is stiff enough to be pushed through the lumen ofa vascular vessel, said body having a uniform outside diameterthroughout a substantial portion of its length, said body having arelatively short distal end portion of said plastic material of reduceddiameter, said end portion having radial passages through the wallthereof, and an elastic tubular balloon normally in a longitudinallyelongated condition attached to and covering said reduced end portion,the proximal end of said balloon being tightly engaged to the proximalend of said reduced portion by a banding means, the distal end of saidballoon being closed by -a substantially hemispherical thickened endportion of the balloon material, said balloon being tightly engaged nearits distal end by a banding means to form an integrated catheter whichthroughout its length provides a uniform, smooth external surfacecapable of being inserted into a restricted surgically formed openingwithout excessive friction and without frictionally deforming saidballoon section as it passes into or is withdrawn from said restrictedopening.

11. A catheter as defined in claim 10, including a source of fluidpressure adapted for connection with the proximal end of the catheterfor inflation of said balloon.

12. A catheter as defined in claim 10, said radial passages beingstaggered longitudinally and circumferentially around said reducedportion to a point close to the distal end of the balloon.

13. A catheter comprising a flexible tube, a balloon surrounding an endportion of the tube, and an inflation passageway in said tube forinflating and deflating the balloon, said balloon having anon-inflatable tip end portion projecting beyond the end of said tubeand forming a soft and highly flexible and resilient tip end portion onthe catheter capable of freely doubling back in a return bend.

14. A catheter as defined in claim 13, said tip end portion of theballoon having a reduced neck portion to enhance its bendability.

15. A catheter comprising a flexible tube having a lumen therein, aballoon surrounding a distal end portion of said tube, balloon inflationopenings in said tube within said balloon communicating with said lumen,and means securing opposite end portions of said balloon to said tube,said tube having a portion of reduced diameter within said balloon andsaid securing means so that the maximum diameter of said securing meansand deflated balloon does not exceed the diameter of the main portion ofsaid tube, said reduced diameter portion of said tube having a furtherreduced end portion within said securing means at the distal end of saidballoon, said balloon having a closed distal end enclosing said furtherreduced end portion of said tube, said lumen terminating at the pointwhere said further reduced end portion begins.

16. A catheter as defined in claim 15, said distal end of said balloonprojecting beyond the end of said tube and forming a soft and highlyflexible tip end portion on the catheter capable of freely doubling backin a return bend.

17. A catheter comprising a flexible tube having a coaxial lumentherein, said tube being continuous to the distal end of the catheterand said distal end being closed, a balloon surrounding the distal endportion of said tube, said balloon having a closed end covering saiddistal end of said tube and forming a soft tip on the catheter, ballooninflation openings in said tube communicating with said lumen atlongitudinally spaced points along said balloon, a winding securing theproximal end of said balloon to said tube, a winding securing a distalend portion of said balloon to said tube at a point close to said distalend of said tube, and surface irregularities on said tube under saidwindings distorting and gripping the balloon material, said balloonmaterial being stretched longitudinally between said windings andsmoothly hugging the surface of said tube when the balloon is deflated.

18. A catheter as defined in claim 17, said closed end of said balloonprojecting beyond the end of said tube and forming a soft and highlyflexible tip end portion on the catheter capable of freely doubling backin a return bend.

References Cited UNITED STATES PATENTS 11/1895 Allen 128-246 8/1936Wolff 128-246 1/1943 Auzin et :al 128-349 X 6/1953 Keeling 128-349 10/1965 Foderick 128-349 7 1902 Hamilton 128-3 44 8/1933 Gerow 128-3492/1955 Cooper 128-276 X 3/1965 Baugh 128-351 6/1965 Andersen 128-3507/1966 Katter 128-344 8/1966 Watkins et a1 128-214 X FOREIGN PATENTS US.Cl. X.R.

